condition mean min max ZT0-3 8.23159 8.23159 8.23159 ZT4-7 6.812865 6.812865 6.812865 ZT8-11 6.151675 6.151675 6.151675 ZT12-15 5.89769 5.89769 5.89769 ZT16-19 7.14966 7.14966 7.14966 ZT20-23 6.88547 6.88547 6.88547